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C# Delete from XML

Posted on 2016-08-08
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Last Modified: 2016-08-09
I have an XML with the following structure
<?xml version="1.0" encoding="utf-8"?>
<Reports>
  <personnel>
     <key value="123">abc</key>
     <key value="456">def</key>
  </personnel>
  <configuration>
     <key value="789">ghi</key>
     <key value="012">jkl</key>
  </configuration>
</Reports>

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I'm building an interface to allow users to maintain the XML allowing them to delete data from the XML file.  I want them to be able to delete by Key.  

Thanks
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Question by:CipherIS
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Expert Comment

by:ste5an
ID: 41747359
So, what is your concrete question?

What do you mean by "interface"? While it is pretty clear in context with your tags, it makes not so much sense with "users". Do you mean an user interface (UI)?

I would use the .NET built-in XML serialization features. Thus you need a schema of your XML. Then you use the XML Schema Definition Tool (Xsd.exe) to generate the class. Then use XmlSerializer class to load your XML into an object graph. Delete your objects and write it back.
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by:CipherIS
ID: 41747375
Yes.  I'm create a GUI to allow the user to look at the values in a grid.  The user will select one of the values from the XML on the Grid then delete it.

Also, this is a winform application.  I'm adding, updating and need to delete data from a file.  How would I serialize the XML?  Examples I've seen for serialization is if I am getting the file from HTTP and streaming it and writing the file.
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by:Fernando Soto
ID: 41747429
Do you already have the XML data loaded into a DataGridView? If so how are you doing this? Will the user need to click a button to actually do the delete?
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by:CipherIS
ID: 41747437
I will be loading the data onto the gridview.  I'm using infragistics UltraGrid.  The winforms will have a combobox which will contain:  personnel, configuration.

The user will select one of the two (there will be a default selection).  The data will displayed in the grid.  The user will either delete from the grid or a button.  

So, I just need to know how the selected row will delete the XML.

I'm still working on figuring out how to get the delete to work with the UltraGrid.  I found the code with Infragistics working on getting it to fire.  It needs to be added to initialize component.  I opened an issue with this also.
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Fernando Soto earned 500 total points
ID: 41747481
Hi CipherIS;

Something like this will work.
// Path and file name of the XML
string fileToModify = "C:/Working Directory/reports.xml";
// Load XML into memory
XDocument xdoc = XDocument.Load(fileToModify);
// this value can be retrieved from the UltraGrid control
string keyToDelete = "ghi";

// Find the value in the XML file
var result = xdoc.Root.Descendants("key").Where(v => v.Value == keyToDelete).ToList();
if (result.Count() > 1)
{
    // More then one key was found. Do something to correct the error
    Console.WriteLine("Error more then one key found");
}
else if ( result.Count() != 0 )
{
    // Delete the XML node and write the document back out to disk
    result.ElementAt(0).Remove();
    xdoc.Save(fileToModify);
}
else
{
    Console.WriteLine("Key was not found.");
}

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by:CipherIS
ID: 41747504
Thanks.  I will try that.  Also, you have provided me code before.  I have a made modification to it.

Where you have
var result = xdoc.Root.Descendants("key").Where(v => v.Value == keyToDelete).ToList();

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I changed to
string element = GetElement(type);
var result = xdoc.Root.Element(element).Descendants("key").Where(v => v.Value == keyToDelete).ToList();

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This allows the key in the correct section to be found.  I implemented this when utilizing the update code that you provided me to ensure that I was updating the correct key in the correct section.

Also, comments have been made about serializing.  I've read up on serializing.  I'm adding, updating, and deleting. Can serialization be added for what I'm doing?  I see how it can be added when I'm streaming a file across http but I'm not doing that.

Thanks.
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Expert Comment

by:Fernando Soto
ID: 41748154
Hi CipherIS;

As to the changes you made to the code snippet I posted that looks fine. As far as using serialize / deserialize of XML you can do that without sending it over a communications link. When you deserialize an XML you are taking and converting it to a Class object. and when you serialize the Class instance you convert that instance into XML. That XML can be on a disk or retrieved from a network. In this case IMHO it would be over kill.
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Author Comment

by:CipherIS
ID: 41748815
Thanks Fernando.  I appreciate the feedback.  I  wasn't too sure and I was researching the heck out of it.  I did find a nice site though.

http://httputility.net/xsd-to-csharp-vb-class.aspx
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Expert Comment

by:ste5an
ID: 41748825
The xsd.exe utitlity is part of Visual Studio and available on the Developer Command prompt.
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Expert Comment

by:Fernando Soto
ID: 41748841
Not a problem CipherIS, glad to help.
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